精确度损失在浮点值使用Java [英] Precision lost in float value using java

问题描述

给出下面的测试代码和它的输出。当我从数值中获得浮点值时，精度就会丢失。谁能告诉我为什么这个行为以及如何处理？

  public static void main（String [] args）
 {
 try 
 {
 java.lang.Number numberVal = 676543.21; 
 float floatVal = numberVal.floatValue（）; 
 System.out.println（Number value：+ numberVal）; 
 System.out.println（float value：+ floatVal）; 
 System.out.println（Float.MAX_VALUE：+ Float.MAX_VALUE）; 
 System.out.println（Is floatVal> Float.MAX_VALUE？+（floatVal> Float.MAX_VALUE））; 
} catch（Exception e）
 {
 e.printStackTrace（）; 
 
 
 
 
 $输出：
 
 
 数字值：676543.21 
浮点值：676543.2 
 Float.MAX_VALUE：3.4028235E38 
是floatVal> Float.MAX_VALUE？ false 
  
为什么float值小于Float.MAX_VALUE？ 
解决方案
我喜欢这些。但是我会快速和无痛的。
 
 
 
浮点数和小数点（也称为浮点数）并不保存在内存中。但是我不希望进入浮点精度与精度问题，我只是指向你的链接 -   http://www.cygnus-software.com/papers/comparingfloats/comparingfloats.htm  
 
 
 
至于你的其他问题，这样说吧，因为浮游物以科学记数法存储。
  floatVal = 6.765432E6 = 6.7 * 10 ^ 6 
 MAX_VALUE = 3.4E38 = 3.4 * 10 ^ 38 
  
 MAX_VALUE是32个数量级更大比你的浮点数。请随时在这里看看 http://steve.hollasch.net/cgindex /coding/ieeefloat.html  
 
 
 
几个月前，我花了很多时间比较和解决一些FP问题... 
 
 
 
尝试比较浮点数时使用小的三角形。 
也许这个链接将帮助你 http://introcs.cs.princeton.edu/ java / 91float /  
 
Given below the test code and its output. When I get float value from number value, precision is lost.. Can anyone tell me why this behaviour and also how to handle this? 
public static void main(String[] args)
    {
        try
        {
            java.lang.Number numberVal = 676543.21;
            float floatVal = numberVal.floatValue();
            System.out.println("Number value    : " + numberVal);
            System.out.println("float value     : " + floatVal);
            System.out.println("Float.MAX_VALUE : " + Float.MAX_VALUE);
            System.out.println("Is floatVal > Float.MAX_VALUE ? " + ( floatVal > Float.MAX_VALUE));
        }catch(Exception e)
        {
            e.printStackTrace();
        }
    }
output:
    Number value    : 676543.21
    float value     : 676543.2
    Float.MAX_VALUE : 3.4028235E38
    Is floatVal > Float.MAX_VALUE ? false
also  why the float value lesser than Float.MAX_VALUE?  
解决方案
I love these. But I'll make it quick and painless.

Floats and decimals (aka floating points) aren't kept in the memory precisely either. But I don't want to get into float accuracy vs precision issues here, i'll just point you to a link - http://www.cygnus-software.com/papers/comparingfloats/comparingfloats.htm

As far as your other question, lemme put it this way, since floats are stored in scientific notation.
floatVal = 6.765432E6 = 6.7 * 10^6
MAX_VALUE = 3.4E38 = 3.4 * 10^38
MAX_VALUE is 32 orders of magnitude bigger than your float number. Feel free to take a look at here as well http://steve.hollasch.net/cgindex/coding/ieeefloat.html

I've spent a great deal of time comparing and fixing some FP issues a few months ago... 

Try to use a small delta when comparing floats.
Maybe this link will help you http://introcs.cs.princeton.edu/java/91float/

                        
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